Re: [Haskell-cafe] advancePtr for ForeignPtr

On Mon, Feb 23, 2009 at 6:48 AM, Henning Thielemann wrote:

On Mon, 23 Feb 2009, Felipe Lessa wrote:

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On Mon, Feb 23, 2009 at 10:12 AM, Henning Thielemann wrote:

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Is still someone on haskell.org ?

Sorry, I don't know :).

I meant ffi@haskell.org

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Do I have to use 'touchForeignPtr' as finalizer of the subarray's ForeignPtr in order to assert that the superarray lives at least as long as the subarray?

This may work, but seems like a fragile hack. Why not

data SubArray a = SA {-# UNPACK #-} !(ForeignPtr a) {-# UNPACK #-} !Int

This would work, but I want to convert from StorableVector to CArray and StorableVector has an offset parameter, which is missing in CArray.

I've used something like the following for that purpose: advanceForeignPtr :: ForeignPtr a -> Int -> IO (ForeignPtr a) advanceForeignPtr fp n = withForeignPtr fp $ \p -> newForeignPtr_ (p `advancePtr` n) -Judah